What are the pros?

What are the cons?

Love TeamViewer - please don't change. I use this mainly for personal clients, but have experienced using the paid program with various vendors over the years. Works, and it works fast, I might add. Way better than Logmein in responsiveness, the free product also allows file transfers.
TeamViewer is now my sweetheart after Logmein ditched us.

Great remote control and sharing tool that seems to work through most firewalls. Only issue found with version 7 was remote access to some OSX clients, otherwise jousts about works with every OS we tried.

You need a host to have a client. Anyway, runs pretty silent in the background until a user connects, then it displays a logged in message on the bottom. Doesn't use a whole lot of memory from what I have seen.